One warning restricts the use of these painkillers to those who need daily, around-the-clock, long-term pain management and for whom non-narcotic drugs haven't worked. A second warning alerts pregnant women to the danger of narcotic withdrawal syndrome in their newborns.

"Today FDA is announcing a set of significant measures to enhance the safe and appropriate use of extended-release and long-acting opioid analgesics," FDA commissioner Dr. Margaret Hamburg said in an afternoon press conference.

Oxycontin, Opana ER, Embeda, Palladone and MS Contin fall into this class of drugs. The medications contain narcotics such as oxycodone or morphine.

These "black box" warning changes will continue to ensure the benefits of these drugs outweigh their risks, Hamburg said. "However, FDA is extremely concerned about the inappropriate use of opioids, which has reached epidemic proportions in the United States," she added.

Although much of the misuse is illegal, even prescribed use can lead to addiction, overdose and death, she said.

"In 2010, an estimated 16,651 people died because of abuse and misuse of opioid drugs," Hamburg said. "There is an increase of more than 300 percent over the past decade. And for each death there is an additional 10 treatment admissions, 32 emergency department visits and 825 nonmedical users of these drugs."

Hamburg said the FDA is trying to find a balance between making these painkillers available for patients who really need them and reducing their misuse and abuse.

The purpose of the new labeling is to make clear that because addiction, abuse and misuse are possible even at recommended doses -- along with the risks of overdose and death -- these drugs should be used only when other non-narcotic drugs have failed or aren't tolerated, or aren't strong enough to manage a patient's pain, the agency says.

These drugs should not be used for "as-needed" pain relief, Hamburg added.

The FDA is also requiring a black box stating that long-term use of the narcotic painkillers by pregnant women can cause narcotic withdrawal syndrome in their newborns.

The syndrome develops in the womb among infants exposed to narcotics and can be life-threatening, the agency said. Symptoms can include poor feeding, rapid breathing, trembling, and excessive or high-pitched crying.

In addition, the FDA is requiring makers of these drugs to conduct new studies and clinical trials to assess the risks of misuse, abuse, increased sensitivity to pain, addiction, overdose and death associated with these medications when used for a long time.

When the wording on the labels is finalized, these changes will also become part of the FDA's strategy to evaluate and mitigate risk, which requires companies to provide educational programs to doctors on how to safely prescribe these drugs.

In addition, companies are required to offer patient medication guides on the safe use, storage and disposal of these narcotic painkillers.

Substance abuse and addiction expert Janina Kean, president and CEO of High Watch Recovery Center in Kent, Conn., said she welcomes "the order for stronger labeling, but believes more needs to be done to reduce overdose deaths -- and to help prevent people from becoming addicted."

She said she'd like to see the FDA "designate specific criteria or a list of chronic pain issues for which opioids can be prescribed."

"Twenty to 25 years ago these drugs didn't even exist, and they keep making them stronger and stronger and I can't understand why," Kean stated. "Today we're prescribing Oxycontin for dental work when we should be using painkillers like Darvocet or Tylenol with codeine, which are more mild and not as readily addictive."